This article covers Side3 2.5Gbps LANカード Realtek RTL8125B チップ.

Overview

The Side3 2.5Gbps LAN Card is a PCI Express x1 network adapter powered by the Realtek RTL8125B chipset. It offers a straightforward way to upgrade a desktop PC to 2.5 Gigabit Ethernet, delivering roughly 2.5 times the bandwidth of standard Gigabit (1000BASE-T). With a power consumption of under 700mW and an aluminum heatsink for thermal management, this card is designed for stable, low-power operation. It also includes a low-profile bracket, making it suitable for compact desktop builds. ## Specifications | Item | Specification | | --- | --- | | Brand | Side3 | | Manufacturer | IOcrest | | Chipset | Realtek RTL8125B | | Interface | PCI Express x1 (compatible with x1, x2, x4, x8, x16 slots) | | Data Transfer Rate | 2.5 Gbps (312.5 MB/s) | | Standards | IEEE 802.3, 802.3u, 802.3ab, 802.3bz | | Power Consumption | < 700mW | | Weight | 80g | | Accessories | Low-profile bracket | | Supported OS | Windows XP / Vista / 7 / 8 / 10 / 11, Linux (up to Kernel 5.6), macOS, DOS |

Connectivity & Compatibility

This card uses a PCI Express x1 interface and can be installed in any PCIe x1, x2, x4, x8, or x16 slot on a desktop motherboard. Auto-negotiation automatically detects the network speed (2.5Gbps, 1000BASE-T, 100BASE-TX, or 10BASE-T) and duplex mode. It also supports Jumbo Frames up to 16KB, which can improve network transfer efficiency. Note that Jumbo Frame support requires all devices on the network path (switches, hubs) to also support it.

Product Info

The Side3 2.5Gbps LAN Card is positioned as an entry-level to mid-range network upgrade solution. The Realtek RTL8125B is a second-generation 2.5GbE controller known for its low power consumption and compact footprint. It is available on for approximately ¥2,480 (tax included), making it a very affordable upgrade. The package includes only the card and a low-profile bracket; no printed manual is included (a PDF manual is available on the product page). View on

Best Use Cases

Ideal for users with a desktop PC that only has a 1Gbps onboard LAN port and who frequently transfer large files to a NAS or file server. The 2.5Gbps speed significantly reduces transfer times. A great fit for creative professionals or remote workers who regularly move large video editing projects or data sets over their local network. * Suitable for budget-conscious users looking to improve their home network performance. Pairing this card with a 2.5GbE switch or router provides a cost-effective high-speed LAN upgrade.

Things to Consider

Ensure your motherboard has a free PCI Express slot (x1 or larger) before purchasing. To achieve full 2.5Gbps speeds, you will need a 2.5GbE-compatible switch or router and at least a CAT5e Ethernet cable. If your existing network equipment only supports 1Gbps, the card will operate at that lower speed. Also, note that the listed Linux kernel support goes up to version 5.6; users of newer distributions should verify driver compatibility.

Product Disclosure (Amazon)

  • Manufacturer: IOcrest
  • Brand: Side3
  • Seller: ランクアップ合同会社
  • Fulfilled by: Amazon
  • ASIN: B09P87LC3H
  • Note: This article covers a manufacturer-made product based on Amazon listing details.